Magnetic testing apparatus



Aug-18,1931. J. A. RODGERS 'LSI QZ MAGNETIC TESTING APPARATUS I I Filed June 2 1925 2 Sheets-Sheet 1 Fig.1.},

INVEN/TOR; JHMES Fl. RODGERS,

BYQAMH/ C V 1/15 ATTORNEYS;

WITNESS:

. Aug. 18, 1931.

J. A. RODGERS 1,819,201

meumr c TESTING APPARATUS 2 Sheets-Sheet 2 Filed June 22, 1925 INVEN TOR. JHMES n. RODGERS,

HIS ATTORNEYS.

Patented Aug. 18, 1931 UNITEB STATES PATENT oFri-cE JAMES A. RODGERS, OF ST. LOUIS, MISSOURI, ASSIGNOR TO THE EMERSON ELECTRIC MFG. 00., OF ST. LOUIS, MISSOURI, A CORPORATION OF MISSOURI MAGNETIC TESTING APPARATUS Application filed June 22, 1925. Serial No. 38,630.-

This invention relates to improvements in magnetic testing apparatus, and consists in the novel construction hereinafter disclosed.

An object of the invention is to provide an apparatus whereby the permeability and the losses due to hysteresis and eddy currents of samples of ferrous material may be tested.

The advantages of the apparatus will be fully apparent from the following detailed description thereof, taken in connection with the accompanying drawings, in which Fig. 1 is a plan view.

Fig. 2 is a front elevation.

Fig. 3 is an end elevation.

Fig. 1 is a diagrammatic view of the apparatus.

In the embodiment of the invention illustrated in the drawings the apparatus is shown as comprising a base 1 to the upper face of which and near the opposite ends thereof are non-magnetic slotted base blocks 2 in each of which is slidably mounted a clamping yoke 3. A standard 4 extends upwardly from each of the blocks 2 and has a threaded opening therein in each of which is mounted a clamping screw 5. The upper arm of each of the yokes 3 is threaded to receive a clamping screw 6.

A U-shaped yoke 7 is mounted on the base, the end arms of which have flat faces in alinement respectively with the inner faces of the yokes 3. Surrounding the central arm of the yoke 7 is a coil 8 having flexible leads 9 and 10, respectively, that connect with binding posts 11 and 12. The sample enclosing coil 13 has leads 14 and 15, respectively, connecting with binding posts 1.6 and 17. The coil 13 is wound with a central rectangular opening therein to receive the test body 18 which may be of elongated laminations of the metal to be tested, or a rectangular section of the metal to be tested. The length of the test body is somewhat greater than the length of the coil 13, which coil is proportioned to fit between the inner edges of the outer arms of the core 7, the ends of the test body extending beyond the coil 13 and into the space between the forward faces of the arms of the core 7 and the inner faces of the yokes 3. By means of the screws 5 and 6 the ends of the test body are brought into close contact with the ends of the core '7. In case th'e'test body is made of laminated strips the strips are held in close contact bydownward pressure of the clamping screwsG, and in the event of a solid sample thescre-ws 6 serve to clamp the ends of the sample downwardly against the blocks 2.

The coil-13 surrounding the test body is in a PIIIDRI X I CI ICUit comprising an alternating current generator 19 which, by means of a lead 20, is connected with the binding postl7 which in turn connects with one end of the coil'13 through the lead 15. A lead 21 is connected to the binding post 16 and through the lead 14 with the opposite end of thecoil13. The lead 21 is connected with the current coil of a wattmeter 22, the opposite end of the current coilof the wattmeter beingfco nnected by a lead 23 with one terminal of an ammeter 24, the opposite terminal of the ammeter 24 being connected with the opposite terminal of the alternating current generator by a lead 25. The wattmeter and ammeter are of known construction. However. for satisfactory operation of the apparatus a wattmeter to give a satisfactory reading at a very low power factor should be employed.

The coil 8 surrounding the core 7 is a secondary coil and is in circuit with the potential coil of the wattmeter through leads 26 connected with the binding post 11 which is connected with the lead 9 at one end of the coil 8, and a lead 27 connected with the binding post 12 which is connected with the lead 10 at the other end of the coil 8, the leads 28 and 29, respectively, serving to complete the connection to the wattmeter from the leads 26 and 27. The leads 26 and 27 connect with opposite sides of a volt-meter 30, it being observed that the induced current in the secondary coil 8 is in parallel connection with the voltmeter and the potential or voltage coil of the wattmeter.

The apparatus is designed for simultaneously determining the combined hysteresis and eddy current losses, and also the permeability of the test body. In determining the combined hysteresis and eddy current losses, commonly called iron losses, the amperage read on the ammeter' is raised to a predeterinc mined reading that is known to give a predetermined flux density in a standard sample. The power input is then read on the wattmeter, which reading gives a value to determine the relation of iron losses in the sample as compared with a standard.

In determining the permeability of the sample a predetermined alternating current from the alternating current generator is passed through the primary coil and the resulting E. M. F. output read on the voltmeter in circuit with the secondary coil indicates the flux density of the sample.

It is thus seen that the factors influencing the magnetic characteristics of the test body may be accurately determined.

What I claim and desire to secure by Letters Patent is An apparatus of the class described comprising a base of non-magnetic material, a U-shaped member supported on the base having contact faces at the ends of the arms thereof, a pair of blocks slidably mounted on the base and movable toward and away from said contact faces, respectively, an overhanging arm on each of said blocks, a clamp device for movinig said blocks toward said contact faces to engage edges of laminated test strips, and clamp devices in each of said overhanging arms adapted to superficially press the laminated test strips into close vertical contact, a test coil having an opening for receiving the test strips disposed intermediate of said blocks, and a coil wound on said U-shaped member.

JAMES A. RODGERS. 

